def main():
    import sys
    input = sys.stdin.readline

    H, W, K = map(int, input().split())

    G = [[0] * W for _ in range(H)]
    for _ in range(K):
        r, c, v = map(int, input().split())
        G[r - 1][c - 1] = v

    pdp = [[0] * 4 for _ in range(W)]
    for r in range(H):
        dp = [[0] * 4 for _ in range(W)]
        left = [0] * 4
        for c in range(W):
            cell = dp[c]

            for k in range(4):
                cell[k] = left[k]

            up = max(pdp[c])
            if cell[0] < up:
                cell[0] = up

            for k in range(2, -1, -1):
                cell[k + 1] = max(
                    cell[k + 1],
                    cell[k] + G[r][c])
            left = cell
        pdp = dp

    # for k in range(4):
    #     for row in range(H):
    #         for col in range(W):
    #             print(dp[row][col][k], end=' ')
    #         print()
    #     print()

    # print(*G, sep='\n')

    ans = max(dp[-1])
    print(ans)


if __name__ == '__main__':
    main() def main():
    import sys
    input = sys.stdin.readline

    H, W, K = map(int, input().split())

    G = [[0] * W for _ in range(H)]
    for _ in range(K):
        r, c, v = map(int, input().split())
        G[r - 1][c - 1] = v

    pdp = [[0] * 4 for _ in range(W)]
    for r in range(H):
        dp = [[0] * 4 for _ in range(W)]
        left = [0] * 4
        for c in range(W):
            cell = dp[c]

            for k in range(4):
                cell[k] = left[k]

            up = max(pdp[c])
            if cell[0] < up:
                cell[0] = up

            for k in range(2, -1, -1):
                cell[k + 1] = max(
                    cell[k + 1],
                    cell[k] + G[r][c])
            left = cell
        pdp = dp

    # for k in range(4):
    #     for row in range(H):
    #         for col in range(W):
    #             print(dp[row][col][k], end=' ')
    #         print()
    #     print()

    # print(*G, sep='\n')

    ans = max(dp[-1])
    print(ans) main import sys sys input = sys.stdin.readline input sys.stdin.readline sys.stdin sys stdin readline H, W, K = map(int, input().split()) H map(int, input().split()) map int input().split() ().split () input split W K [0] * W for _ in range(H) for _ in range(H) _ range(H) range H for _ in range(H) [0] * W [0] 0 W G = [[0] * W for _ in range(H)] G [[0] * W for _ in range(H)] for _ in range(K):
        r, c, v = map(int, input().split())
        G[r - 1][c - 1] = v

     _ range(K) range K r, c, v = map(int, input().split()) r map(int, input().split()) map int input().split() ().split () input split c v G[r - 1][c - 1] = v G[r - 1][c - 1] [r - 1] G r - 1 r 1 c - 1 c 1 v [0] * 4 for _ in range(W) for _ in range(W) _ range(W) range W for _ in range(W) [0] * 4 [0] 0 4 pdp = [[0] * 4 for _ in range(W)] pdp [[0] * 4 for _ in range(W)] for r in range(H):
        dp = [[0] * 4 for _ in range(W)]
        left = [0] * 4
        for c in range(W):
            cell = dp[c]

            for k in range(4):
                cell[k] = left[k]

            up = max(pdp[c])
            if cell[0] < up:
                cell[0] = up

            for k in range(2, -1, -1):
                cell[k + 1] = max(
                    cell[k + 1],
                    cell[k] + G[r][c])
            left = cell
        pdp = dp

    # for k in range(4):
    #     for row in range(H):
    #         for col in range(W):
    #             print(dp[row][col][k], end=' ')
    #         print()
    #     print()

    # print(*G, sep='\n')

     r range(H) range H [0] * 4 for _ in range(W) for _ in range(W) _ range(W) range W for _ in range(W) [0] * 4 [0] 0 4 dp = [[0] * 4 for _ in range(W)] dp [[0] * 4 for _ in range(W)] left = [0] * 4 left [0] * 4 [0] 0 4 for c in range(W):
            cell = dp[c]

            for k in range(4):
                cell[k] = left[k]

            up = max(pdp[c])
            if cell[0] < up:
                cell[0] = up

            for k in range(2, -1, -1):
                cell[k + 1] = max(
                    cell[k + 1],
                    cell[k] + G[r][c])
            left = cell
         c range(W) range W cell = dp[c] cell dp[c] dp c for k in range(4):
                cell[k] = left[k]

             k range(4) range 4 cell[k] = left[k] cell[k] cell k left[k] left k up = max(pdp[c]) up max(pdp[c]) max pdp[c] pdp c if cell[0] < up:
                cell[0] = up

             cell[0] < up cell[0] cell 0 up cell[0] = up cell[0] cell 0 up for k in range(2, -1, -1):
                cell[k + 1] = max(
                    cell[k + 1],
                    cell[k] + G[r][c])
             k range(2, -1, -1) range 2 -1 -1 cell[k + 1] = max(
                    cell[k + 1],
                    cell[k] + G[r][c]) cell[k + 1] cell k + 1 k 1 max(
                    cell[k + 1],
                    cell[k] + G[r][c]) max cell[k + 1] cell k + 1 k 1 cell[k] + G[r][c] cell[k] cell k G[r][c] [r] G r c left = cell left cell pdp = dp pdp dp ans = max(dp[-1]) ans max(dp[-1]) max dp[-1] dp -1 print(ans) print ans if __name__ == '__main__':
    main() __name__ == '__main__' __name__ '__main__' main() main def main():
    import sys
    input = sys.stdin.readline

    H, W, K = map(int, input().split())

    G = [[0] * W for _ in range(H)]
    for _ in range(K):
        r, c, v = map(int, input().split())
        G[r - 1][c - 1] = v

    pdp = [[0] * 4 for _ in range(W)]
    for r in range(H):
        dp = [[0] * 4 for _ in range(W)]
        left = [0] * 4
        for c in range(W):
            cell = dp[c]

            for k in range(4):
                cell[k] = left[k]

            up = max(pdp[c])
            if cell[0] < up:
                cell[0] = up

            for k in range(2, -1, -1):
                cell[k + 1] = max(
                    cell[k + 1],
                    cell[k] + G[r][c])
            left = cell
        pdp = dp

    # for k in range(4):
    #     for row in range(H):
    #         for col in range(W):
    #             print(dp[row][col][k], end=' ')
    #         print()
    #     print()

    # print(*G, sep='\n')

    ans = max(dp[-1])
    print(ans) def main():
    import sys
    input = sys.stdin.readline

    H, W, K = map(int, input().split())

    G = [[0] * W for _ in range(H)]
    for _ in range(K):
        r, c, v = map(int, input().split())
        G[r - 1][c - 1] = v

    pdp = [[0] * 4 for _ in range(W)]
    for r in range(H):
        dp = [[0] * 4 for _ in range(W)]
        left = [0] * 4
        for c in range(W):
            cell = dp[c]

            for k in range(4):
                cell[k] = left[k]

            up = max(pdp[c])
            if cell[0] < up:
                cell[0] = up

            for k in range(2, -1, -1):
                cell[k + 1] = max(
                    cell[k + 1],
                    cell[k] + G[r][c])
            left = cell
        pdp = dp

    # for k in range(4):
    #     for row in range(H):
    #         for col in range(W):
    #             print(dp[row][col][k], end=' ')
    #         print()
    #     print()

    # print(*G, sep='\n')

    ans = max(dp[-1])
    print(ans) main
def main():
    import sys
    input = sys.stdin.readline

    H, W, K = map(int, input().split())

    G = [[0] * W for _ in range(H)]
    for _ in range(K):
        r, c, v = map(int, input().split())
        G[r - 1][c - 1] = v

    pdp = [[0] * 4 for _ in range(W)]
    for r in range(H):
        dp = [[0] * 4 for _ in range(W)]
        left = [0] * 4
        for c in range(W):
            cell = dp[c]

            for k in range(4):
                cell[k] = left[k]

            up = max(pdp[c])
            if cell[0] < up:
                cell[0] = up

            for k in range(2, -1, -1):
                cell[k + 1] = max(
                    cell[k + 1],
                    cell[k] + G[r][c])
            left = cell
        pdp = dp

    # for k in range(4):
    #     for row in range(H):
    #         for col in range(W):
    #             print(dp[row][col][k], end=' ')
    #         print()
    #     print()

    # print(*G, sep='\n')

    ans = max(dp[-1])
    print(ans)


if __name__ == '__main__':
    main()
